Video-based security systems are commonly employed by businesses and other facilities, such as banks, stores and airports. Video-based security systems utilize a sensing device, such as a video camera, to obtain and record images within the video camera's field-of-view. The images recorded by the video camera may be monitored by a human operator, either in real-time or on a delay, and/or stored for future use.
In an effort to keep costs down, many security systems are designed to utilize a small number of wide angle video cameras. However, while stationary camera systems provide a wide coverage area, they typically do not capture high resolution images.
An alternative to the wide angle video camera system is an active camera system. An active camera system may utilize a small number of pan-tilt-zoom (PTZ) cameras that can operate in a wide-angle mode or a PTZ mode. An active camera system may use one or more individual cameras which operate in a wide-angle mode, until a target of interest is detected, and then may automatically switch to a PTZ mode. Once in PTZ mode the PTZ camera may zoom in and/or track the target as long as it remains in the camera's direct line of sight. While in PTZ mode, the PTZ camera may be able to capture high resolution images of the target.
Calibration of the PTZ camera is an important step in ensuring proper operation of an active camera system. Once the PTZ camera is calibrated, the response and stability of a PTZ camera controller can be fine tuned. While manual calibration of the PTZ camera is desirable, it may not always be possible. For example, a deployed PTZ camera in need of calibration may be difficult to reach rendering manual calibration impractical.